Put the leek greens, washed carrots peels, celery leaves, garlic, onions, bouquet garni, and the bay leaf on the bottom of the Dutch oven. Place the chicken on top and add the salt and black peppercorns. Cover with 12 cups of cold, filtered water.
Cover and bring to a boil, then reduce heat to simmer. Cook until very tender and 165°F; 40 to 55 minutes depending on the size and freshness of your chicken.
When tender, remove the chicken and put it on a plate. Cover loosely with foil. Leave to cool then tear into large chunks. Remove the veggies with a large splotted spoon or a metal spider and discard.
Strain the stock by pouring into a fine mesh strainer placed over a large bowl. You should have 10 cups of chicken stock.
Pour the stock back into the Dutch oven. Add the long grain rice, chunky leeks, celery, carrots, and prunes. Simmer covered for 30 minutes over medium low heat.
Add the sliced leeks, reserve some for garnish, salt, and black pepper. Cook for 10 minutes. Taste and adjust seasonings, so the broth is to your liking.
Divide the chunks of chicken into 6 bowls (50g to 75g), ladle soup on top and garnish with fresh parsley and thin leek coins. Serve immediately with a slice of fresh, homemade crusty bread like our Cob loaf.